The most common and most likely answer to this crossword clue is the 9 letter word FORTHWITH
I've seen this crossword clue in The Guardian
F
O
R
T
H
W
I
T
H
More clues leading to the result FORTHWITH
Buddy explains!

The straight part
We know that "straight away" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case straight away = forthwith.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does FORTHWITH mean?
FORTHWITH adverb- Without delay; immediately.